Such a coupling is known from EP-A-0202592, a piston in a cylindrical housing being shiftable, and moving at its front end clamping jaws radially adjustable by axial displacement via a ramp arrangement. The induced axial reciprocating movement of the piston is effected by a hand lever.
This known plug coupling is, however, only suitable for coupling fluid lines such as filling hoses for tanks under relatively low pressure since, on disconnection, the filling lines remain under pressure, the roll of the clamping jaws being under considerable pressure due to axial pressure application. Disconnection by radially pushing the clamping jaws apart is thus only possible by considerable power application even with corresponding power step-up of the hand lever. Thus, ventilation valves are known at filling tanks or pumps; said valves can, however, be operated in a separate stage after operation of a further shut-off valve and before release of the coupling. This can, however, lead to high safety risk especially due to leakage of inflammable of explosive fluids if operation is incorrect, e.g., if individual valves are operated in the wrong order. This is true of filling stations where vehicles are tanked up with gaseous fuel.
German Disclosure Publication 28 23 886 (corresponding to U.S. application Ser. No. 801,719) shows a similar coupling device with a shiftable piston actuated by eccentric handle and with a clamping jaw actuated by a second handle. As two handles have to be actuated by the operator the handling of the coupling device is rather complicated and may cause danger, if the two handles are changed by mistake.
U.S. Pat. No. 3,474,827 has a coupling device having a flow passage through it; a valve member at one end of the passage can be moved to open or close the coupling device by an operating lever. Connection of the coupling device to an adapter is made by rotating the coupling device relative to the adapter and causing an engagement of notches within recesses. However, rotating the coupling device is complicated and uncomfortable to use. The same is true with respect to further French Patent 12 35 444, as two levers have to be actuated to connect or disconnect the coupling device.